This invention relates to solvent evaporators, and in particular to laboratory scale rotary evaporators.
Current laboratory practice makes use of the popularly named "rotary evaporator" to either concentrate or remove solvents such as alcohol, acetone, water, and so on, from various samples. The solvents to be concentrated or removed are typically placed in a pear shaped PYREX (a registered trademark of Corning Glass Works) flask which is then connected to a motor which will cause the flask to be rotated. Means are provided for connecting the flask to a source of vacuum which usually includes a means for condensing the evaporating solvents as well as a vacuum pump, and the flask is usually placed in a water bath which can be temperature controlled with thermostatically controlled heating. Under these conditions of flask rotation and vacuum the solvents are evaporated efficiently while frothing and bumping that often accompanies a vacuum distillation is suppressed to various degrees. Both batch and continuous process rotary evaporations of this type are described in U.S. Pat. No. 2,797,747 and U.S. Pat. No. 2,865,445.
While the above mentioned devices have proven to be generally satisfactory, there are problems inherent to their design which has been addressed by U.S. Pat. Nos. 4,790,911 and 4,913,777. In these two patents a solvent evaporator is disclosed which does away with the necessity for rotating the solvent flask by placing a magnetically driven cylinder within the flask. A rotatable magnet exterior to the flask causes the cylinder within the flask to rotate in synchrony, thereby developing a thin solvent film on both the exterior and interior of the cylinder, providing for efficient solvent evaporation, and frothing and bumping control, when a vacuum and thermostatically controlled heating is applied to the solvent container. A conventional heated water bath can be used to expedite solvent evaporation, or, since the solvent container is stationary, hot plates or heating mantles can be used as a source of thermostatically controlled heating. While the above described stationary evaporator can eliminate the cumbersome and expensive water bath heating methods usually employed, ordinary conductive heaters provide slower evaporation rates in comparison to the standard water bath. To overcome this, the instant invention makes use of infra-red heating to provide comparable solvent removal efficiencies to water bath procedures without the use of a water bath, while at the same time maintaining the simplicity of operation of the stationary solvent evaporator.
Accordingly it is a primary object of the invention to provide an efficient rotary evaporator without the necessity for utilizing a water bath.
Another object of the invention is to provide a rotary evaporator in which solvent evaporation is expedited by means of infra-red radiation.
Still another object of the invention is to provide a stationary solvent container for rotary evaporation procedures expedited by means of infra-red radiation.
An additional object of the invention is to provide an infra-red heated solvent evaporation in which the entire contents of the container are simultaneously heated by means of infra-red radiation.
A further object of the invention is to provide simple and economical temperature control within a solvent container being heated by means of infra-red radiation.
Additionally an object of the invention is to provide for automatic monitoring of the temperature within a solvent container in a simple and economical manner.